How about the pressure angle of helical gear?
The specific formulas are: TN (alpha n) = TN (alpha T) * cos betaAngle of end pressure of T. Beta helix angle.The normal pressure angle of alpha n is generally 20 degrees.
The pressure angle of the helical gear is divided into the end pressure angle and the normal pressure angle.The end face pressure angle is not a fixed value, but varies with the screw angle.
There are some on this mechanical design manual. You can look it up
